The conventional eddy-current brakes have the problem that the weight of the brake per braking torque produced is large in comparison with other types of brake. Generally, eddy-current brakes comprise a rotator made of a ferromagnetic material and electromagnets, which are arranged so that the rotator will intercept the magnetic flux, wherein a braking force is produced by the eddy current generated in the rotator. In such brakes, the smaller the electric resistance of the rotator material, the greater is the braking torque developed if the other conditions, namely electromagnet coil line diameter, number of turns of coil, electric current applied and space between electrode and rotator are the same. It is an essential condition for such brakes that the rotator is made of a ferromagnetic material. Therefore, whatever magnetic material is used, there is produced no remarkable difference in the torque developed. This means that the eddy-current brakes are less suited for producing a large braking torque than the brakes of other systems. An invention which has improved this point and enabled the eddy-current brakes to develop a large braking torque is disclosed in PCT/JP87/00893 applied by the present inventor (which corresponds to U.S. Ser. No. 07/294,568 filed Dec. 16, 1988, now U.S. Pat. No. 4,937,483 issued June 26, 1990). The invention of PCT/JP87/00893 proposes the improvements in which the rotator surface opposing the electromagnet electrodes is clad with a metallic layer composed of a non-magnetic material having a greater electroconductivity than the rotator material to thereby increase the eddy current generated in the rotator while the coils of electromagnets are enclosed by a magnetic pole case made of a ferromagnetic material, and each electromagnet is so designed that its sectional area through which the line of magnetic force of said magnetic pole case passes will be equal to or greater than the cross-sectional area of the magnetic pole so as to shorten the magnetic path of the electromagnet to thereby increase the strength of its magnetic field.
The present invention is intended to provide an eddy-current brake in which further improvements have been made on the metallic layer to increase the eddy current generated in the rotator while enhancing the cooling performance of said metallic layer and also making it peel-resistant.